Dentin Microtensile Bond Strength Research Articles

Evaluating the advancements in a recently introduced universal adhesive compared to its predecessor

Background/purposeThe dental adhesive market is constantly evolving to meet the demands of dentists and patients, but new products and upgrades should be rigorously evaluated before being used in clinical practice. This study investigated the physicomechanical properties and dentin bonding efficacy of a newly upgraded universal adhesive compared to its predecessor. Materials and methodsTwenty-four molars were divided into four groups (n = 6/group) based on adhesive (new vs. predecessor) and application mode [self-etch (SE) vs. etch-and-rinse (ER)] for evaluating their dentin microtensile bond strength (μTBS), failure pattern, and bonding interface. Additional thirty-six molars' crowns were perpendicularly sectioned to obtain flat mid-coronal dentin discs. The opposing dentin surfaces of each disc received contrasting treatments (new/predecessor adhesive applied in SE/ER mode), resulting in six interventions. The bonded discs (n = 6/intervention) were used to assess the adhesives' survival probability employing a double-sided μTBS test. The other physicomechanical properties examined were adhesives’ oxygen inhibition layer (OIL), viscosity, hardness, elastic modulus, degree of conversion (DC), and in-situ DC. ResultsBoth adhesive versions showed similar μTBS (P > 0.05), failure pattern (P > 0.05), and survival probability (P > 0.008). ER mode promoted resin tag formation and exhibited a slender adhesive layer for both adhesives. The newer adhesive version showed a thinner adhesive layer in general with narrower OIL (P < 0.001), less viscosity (P < 0.001), higher hardness (P < 0.05), elastic modulus (P < 0.05), DC (P < 0.001), and in-situ DC (P < 0.001). ConclusionWhile the newly updated adhesive had superior physicomechanical properties with more fluidity, its dentin bonding efficacy and survival probability were comparable to its predecessor.

Effects of immersion in 4-methacryloyloxyethyl trimellitate anhydride/methyl methacrylate-tri-n-butyl borane resin-activated liquid on microtensile bond strength of root canal dentin

Background/purpose4-methacryloyloxyethyl trimellitate anhydride/methyl methacrylate-tri-n-butyl borane (4-META/MMA-TBB) resin is used for indirect restorations. We aimed to evaluate effects of immersion in 4-META/MMA-TBB-activated liquid on the bond strength of root canal dentin. Materials and methodsWe used freshly extracted single-rooted human teeth. After decoronation, each root was vertically sectioned into halves; their dentin walls were polished and flattened. The control group underwent dentin treatment with Green Activator. The immersion group was treated with Green Activator and Teeth Primer and immersed in 4-META/MMA-TBB-activated liquid. After bonding the resin blocks with Super-Bond, microtensile bond strength (μTBS) tests were performed (n = 6), and fracture surfaces were analyzed. Before surface treatment, dentin was immersed in a sodium fluorescein solution for 3 h, and resin blocks were bonded with Super-Bond with rhodamine B as in the bond strength test. The bonded cross section was observed using confocal laser scanning microscopy (CLSM). ResultsμTBS was significantly higher in the immersion group than in the control group (61.5 [51.3–66.7] vs. 33.0 [20.4–57.8] MPa; P < 0.05). Fracture mode analysis showed that, compared with the control group, the immersion group had a significantly lower rate of adhesive failure at the dentin interface and a significantly higher rate of cohesive failure in Super-Bond (P < 0.01). CLSM showed a water droplet-like accumulation of fluorescein dye above the hybrid layer in the control group, not in the immersion group. ConclusionImmersion in a 4-META/MMA-TBB-activated liquid inhibited water exudation from the root canal dentin and improved the bond strength.

Effect of flavonoid-based experimental primers on dentin microtensile bond strength and interface morphology

ObjectivesThis study evaluated the effect of four flavonoid-based experimental primers on the dentin bond strength (μTBS) and the bonding interface morphology of an adhesive. Materials and methodsFour experimental primer solutions containing two different flavonoids (Kaempferol and Naringin) in two concentrations (10 mM and 20 mM) were applied for 30 s or 60 s on dentin after phosphoric acid etching, followed by an etch-and-rinse adhesive system. A Negative Control (NC) consisting of dentin not treated with experimental primer solutions and Positive Controls (PC) that used 0.2% chlorhexidine solution for 30 and 60 s were also tested. Eighty-eight teeth were selected for dentin μTBS (n = 8). Dentin-adhesive interface morphology (n = 4) were analyzed by confocal laser scanning microscopy (CLSM). Data were analyzed by mixed three-way ANOVA (μTBS) and two-way ANOVA (CLSM) (α = 0.05). Dentin μTBS was analyzed at 24 h and one-year, while the bonding interface morphology was evaluated at 24 h. ResultsRegarding μTBS, no statistical difference was found between the experimental groups and NC at 24 h. However, most experimental primers applied for 60 s presented higher values compared to NC at one-year. Hybrid layer formation and adhesive infiltration was observed in all groups by CLSM. ConclusionsThe application of flavonoid-based experimental primers for 60 s was able to produce higher μTBS than those obtained with NC and PC after one-year of artificial aging, without interfering with interface morphology.

The Effect of Matrix Metalloproteinase Inhibitors on the Microtensile Bond Strength of Dentin Bonding Agents in Caries Affected Dentin: A Systematic Review.

Matrix metalloproteinases (MMPs) cause degradation of the dentinal matrix, as they act actively on collagen fibrils, leading to their deterioration and collapse. MMP inhibitors are known to be used for the pre-treatment of human dentin before bonding. Most studies on the MMP inhibitors examined the effect of MMP inhibitors on bonding to sound dentin (SD), but few examine their effect on bonding to caries affected dentin (CAD). This systematic review aims to identify and summarize studies that have applied MMP inhibitors for pre-treatment of CAD, and examine the microtensile bond strength (µTBS), bond durability, and the mode of failure. A systematic review was performed using the PubMed database according to the PRISMA guidelines. A total of 785 original articles published between 2010 and 2022 were initially retrieved. Six studies were selected based on predefined inclusion-exclusion criteria, and their outcomes were extracted and analyzed. The methodological quality assessment was performed using a combined checklist that utilizes the reporting criteria mentioned in the checklist for reporting in-vitro studies guidelines and guidelines for reporting pre-clinical in vitro studies on dental materials. All six studies included here showed a definitive increase of the µTBS when MMP inhibitors were applied to the CAD. The mode of failure was found to be predominantly adhesive in nature. The deviation in the values of µTBS was approximately 2-5 MPa on immediate and delayed testing. MMP-inhibiting agents could be considered for the pretreatment of teeth with CAD as a part of their tooth preparation area, thereby allowing the clinician to retain CAD and bond to the CAD without endangering the vital pulp.

Effect of light-curing silver diamine fluoride on microtensile bond strength of primary carious dentin restored with glass ionomer cement: In vitro study

Effect of light-curing silver diamine fluoride on microtensile bond strength of primary carious dentin restored with glass ionomer cement: In vitro study

Microtensile Bond Strength of Total-Etch and Self-Etch Universal Adhesives Containing 10-MDP: A Systematic Review

A systematic review was performed to compare the human dentin microtensile bond strength of universal adhesives with 10-MDP when used as total-etch and self-etch strategies. Literature search was done on October 2019 without limitations on the language of publication, in four databases: PubMed, Web of Science, Scopus, and EBSCO. Additional manual search was done for the grey literature articles: OpenGrey and OpenThesis. Studies that evaluated the dentin bond strength of universal adhesives with 10-MDP using total-etch and self-etch strategy from the year 2000 up till October 2019 were included. The initial search resulted in 5121 references: 2234 from PubMed, 1814 from Scopus, 516 from Web of Science, 553 from EBSCO and 4 from OpenThesis. After full text analysis, 30 references were included in this systematic review. Seven different universal adhesives with 10-MDP were evaluated for dentin microtensile bond strength comparing total-etch and self-etch strategies: Single Bond Universal/Scotchbond Universal (3M ESPE), All Bond Universal (Bisco), Clearfil Universal Bond (Kuraray), G-Premio Bond (GC Corp), Tetric Bond Universal (Ivoclar Vivadent), Ambar Universal (FGM) and One Coat 7 Universal (Coltene). The total-etch strategy improved the dentine microtensile bond strength compared to self-etch strategy for all universal adhesives when stored in all three conditions: 24h, thermocycling and long-term immersion according to ISO (TS 11405:2015(E)). The evidence suggests that microtensile bond strength of universal adhesives containing 10-MDP may be improved utilizing total-etch strategy compared to self-etch strategy. This study provides valuable information on the importance of appropriate dentin adhesives strategy that affect success rate of restorations, which helps clinicians to make informed decisions on the strategy to be used during restorations in practice.

Effect of a novel pretreatment on the microtensile bond strength of universal adhesives with dentin

Background/purpose: The quality of the hybrid layer is of great importance for dentin bonding. The purpose of this study was to develop a novel copper-based pretreatment and investigate the effect of the pretreatment combined with universal adhesives on the dentin bond strength. Materials and methodsEtch-and-rinse adhesive Single Bond 2 (SB2) and two universal adhesives Prime Bond Universal (PBU) and Single Bond Universal (SBU) were selected. The dentin surfaces were pretreated with CuSO4 solution and K2HPO4 solution in turn (Cu–P pretreatment), and the adhesive was applied following the manufacturer's instructions. There were four groups of Cu–P pretreatment: HH-Cu (1.5 mol/L CuSO4 + 1.0 mol/L K2HPO4); H–Cu (0.15 mol/L CuSO4 + 0.1 mol/L K2HPO4); L-Cu (0.015 mol/L CuSO4 + 0.01 mol/L K2HPO4); and LL-Cu (0.0015 mol/L CuSO4 + 0.001 mol/L K2HPO4). The microtensile bond strength (μ-TBS) and fracture mode were determined. The dentin surface after pretreatment and the antimicrobial properties of the pretreatment agent were also evaluated. ResultsThe minimum inhibitory concentration and minimum bactericidal concentration of Cu–P pretreatment were 0.012 mol/L CuSO4 + 0.008 mol/L K2HPO4. Combined with SB2, the H–Cu and L-Cu groups showed a higher μ-TBS (P < 0.01), while the HH-Cu group showed a lower μ-TBS (P < 0.001), and the LL-Cu group showed a similar μ-TBS with the control group without Cu–P pretreatment. Combined with universal adhesives PBU and SBU, the H–Cu and L-Cu groups also showed significantly increased μ-TBS (P < 0.01). ConclusionThe copper-based pretreatment in combination with universal adhesives improved the dentin microtensile bond strength.

Comparative Evaluation of Microtensile Bond Strength in Three Different Dentin Luting Agents: An In vitro Study.

Long-term clinical success on indirect restorations is largely determined by bonding efficiency of the luting agent, with adhesion to dentin being the main challenge. Therefore, aim of this study was to assess the microtensile bond strength when using flowable resin composite, preheated resin composite and dual self-adhesive resin cement as dentin luting agents. Occlusal thirds of molar teeth were cut and randomly divided into 3 groups to be cemented: RelyX™U200, Filtek™ Z250 XT- preheated to 70° and Filtek Flow™ Z350XT. They were then thermocycled 5000 times between 5+/-2°C and 55+/-2°C. Subsequently, 10 microbars per group were prepared. The 30 samples were placed in saline solution for 24 hours at room temperature prior to microtensile test. This was performed with a digital universal testing machine at a crosshead speed of 0.5 mm/min. The bond strength values obtained were analyzed in Megapascals (MPa). Measures of central tendency such mean and measures of dispersion such standard deviation were used. In addition, the Kruskall Wallis non-parametric test with Bonferroni post hoc test was applied, considering a significance value of 5% (P < 0.05), with type I error. The dentin microtensile bond strengths of preheated resin composite, flowable resin composite and dual self-adhesive cement were 6.08 ± 0.66 Mpa, 5.25 ± 2.60Mpa and 2.82 ± 1.26Mpa, respectively. In addition, the preheated resin composite exhibited significantly higher microtensile bond strength compared to the dual self-adhesive cement (P < 0.001). While the flowable resin composite showed no significant difference with the dual self-adhesive cement (P = 0.054) and the preheated resin composite (P = 0.329). The microtensile bond strength in dentin was significantly higher when using a preheated resin composite at 70°C as a luting agent compared to dual self-adhesive cement. However, the preheated resin composite showed similar microtensile bond strength compared to the flowable resin composite.

Collagen Cross-Linking Lignin Improves the Bonding Performance of Etch-and-Rinse Adhesives to Dentin.

To evaluate the biomodification ability of lignin used as pre-treatment in human dentin before the application of an etch-and-rinse adhesive. Experimental hydroethanolic solutions with different cross-linking agents were used: 6.5% proanthocyanidins (PAC, from grape-seed extract); 2% cardanol (CARD, from cashew-nut shell liquid); lignin (LIG, from eucalyptus) at 1, 2 or 4% concentrations. The negative control (NC) was ethanol 50 v%. Extracted molars were prepared, and dentin microtensile bond strength (μTBS) was evaluated after 24 h water storage or 10,000 thermocycling aging. Further specimens were processed for SEM nanoleakage, micropermeability confocal microscopy evaluation and in situ degree of conversion (DC) through micro-Raman spectroscopy. Demineralized dentin sticks were submitted to a three-point bending test to evaluate the elastic modulus (E) before and after 1 min biomodification using the tested solutions. Moreover, it was also evaluated the mass changes and hydroxyproline (HYP) release after 4-weeks of water storage. Vibrational collagen crosslinking identification was evaluated through micro-Raman spectroscopy. The results were analyzed by analysis of variance (ANOVA) and Tukey’s test (α = 0.05). A significant reduction in μTBS was observed in groups NC (p < 0.001) and CARD (p = 0.026). LIG-4% showed no significant reduction in μTBS after aging (p = 0.022). Nanoleakage micrographs showed hybrid layer protection with all agents, but reduced micropermeability was attained only with lignin. Polymerization was negatively affected in the presence of all tested cross-linking agents, except LIG-1%. Lignin and cardanol increased the dentin E values, but only lignin reduced the mass loss in dentin specimens. Effective collagen crosslinking (1117 cm−1 and 1235 cm−1) was detected for all agents. HYP release was significantly lower with LIG-1% than NC (p < 0.001). Lignin was able to perform collagen cross-linking and prevent the degradation of unprotected dentin collagen, thereby improving the bonding performance of the composite restorations performed in this study.

Bonding interface and dentin enzymatic activity of two universal adhesives applied following different etching approaches

ObjectivesEtching approaches [37% phosphoric acid, self-etching, 10–3 solution (3% ferric chloride dissolved in 10% citric acid), or 1.4% nitric acid] were evaluated regarding enamel shear bond strength (24 h), dentin microtensile bond strength (24 h and 2 years), failure mode, enzymatic activity of the hybrid layer, and nanoleakage (24 h and 2 years) of Prime&Bond Universal (PBU, Dentsply-Sirona) and Gluma Bond Universal (GBU, Kulzer). MethodsAdhesives were applied on blot-dried (wet-bonding, positive control) or air-dried (remaining groups) dentin after acid-etching (15 s) or in self-etch mode. Enamel and dentin bond strength tests used 160 human teeth (n = 10). Failure mode of tested samples and nanoleakage within the dentin-adhesive interface (n = 5) were analyzed by scanning electron microscopy. Dentin enzymatic activity was investigated by in situ zymography (n = 3). ResultsEnamel bond strengths did not differ statistically among groups. Wet-bonding with 37% phosphoric acid showed similar dentin bond strength compared to 10–3 solution or 1.4% nitric acid at 24 h for both adhesives. None of the etchants inhibited enzymatic activity, and all groups showed dentin bond strength reduction after 2-year storage. GBU showed higher nanoleakage. Experimental etchants did not affect enamel bond strength. Dentin bond strength was not stable after 2 years, despite promising 24-hour results. SignificanceThis study suggests multiple etching approaches to optimize and achieve stable dentin bonding, while also offering in-depth information about the performance of recently released universal adhesive systems.

Marginal microleakage and modified microtensile bond strength of Activa Bioactive, in comparison with conventional restorative materials.

This study aimed to assess the enamel and dentin marginal microleakage and dentin microtensile bond strength (μTBS) of ACTIVA BioACTIVE Restorative with and without a bonding agent compared with conventional restorative materials. For enamel and dentin microleakage, Class II boxes were prepared in the mesial (1 mm under the cementoenamel junction) and distal (1 mm above the cementoenamel junction) surfaces of 90 extracted human third molars. The teeth were randomly divided into five groups (n = 18): Group Z (G-Premio Bond + Filtek Z250 XT), Group X (G-Premio Bond + X-tra fil bulk-fill), Group AA (G-Premio Bond + Activa Bioactive restorative), Group A (Activa Bioactive restorative), and Group G (dentin conditioner + Fuji II LC Improve). The teeth were thermocycled, and their microleakage was quantified using the dye penetration test under a stereomicroscope. For dentin μTBS measurement, 12 specimens were fabricated in metal molds (1 × 1 × 12 mm³) for each group mentioned above, and a universal testing machine measured their μTBS. Data were analyzed using one-way analysis of variance (ANOVA), the Kruskal-Wallis test, and multiple comparisons tests. Significant differences were noted among the groups in marginal microleakage and μTBS (p < .001). The highest mean microleakage scores at the enamel and dentin margins were noted in Group A, which had significant differences with other groups (p < .001). The highest μTBS was found in Group X, with significant differences with Group G and Group A (p < .05). The lowest µTBS was noted in Group A, with significant differences with Groups X, Group AA, and Group Z (p < .001). Activa Bioactive without a bonding agent showed significantly lower µTBS to dentin, and higher microleakage at the enamel and dentin margins. Application of adhesive resin with Activa Bioactive provided a dentine bond strength and marginal seal comparable to other restorative materials.

The Effect of Different Condition of Pulpal Pressure on Microtensile Bond Strength of Several Dentin Bonding Agents on Deep and Superficial Dentin.

The objective of this study was to examine the effect of different conditions of simulated hydrostatic pulpal pressure on the μTBS of HEMA-based and HEMA-free dentin bonding agents (DBAs). The influence of dentin location (deep and superficial) on μTBS was also evaluated. Flat coronal dentin surfaces of extracted human molars were prepared. Three groups of resin-bonded specimens were exposed to different pulpal pressures. Pulpal pressure was maintained for 20 min for each group. A flowable resin composite was used for coronal build-up. The bonded teeth were sectioned and, after 24 h of water storage, stressed to failure using the microtensile tester (μTBS). Failed samples were analyzed by SEM inspection. HEMA-based DBAs were much more sensitive to pulpal pressure conditions than non-HEMA-containing DBAs. Pulpal pressure had a greater influence in deep dentin. The HEMA-free DBA was insensitive to the presence or absence of pulpal pressure condition. SEM inspection confirmed a relationship between the presence of voids inside the HEMA-based DBAs layer and the lower μTBS results. HEMA-based DBAs are more sensitive to pulpal pressure conditions than HEMA-free DBAs. Interestingly, HEMA-free DBA showed a greater number of water droplets at resin–dentin interface in all tested conditions.

Mussel wet adhesion inspired using dopamine methacrylamide as a primer to improve dentin adhesion

This study aimed to evaluate whether a mussel wet adhesion inspired catechol-functionalized primer (dopamine methacrylamide, DMA) can increase microtensile bond strength (μTBS) of dentin–resin adhesion and improve the bonding interface in vitro. DMA was synthesized and characterized by proton nuclear magnetic resonance spectral analysis and high-resolution mass spectrometer analysis. A total of 50 flat dentin slabs of 50 human 3rd molars were prepared and allocated into two groups for DMA application (the DMA and experimental groups) and distilled water (the DW and control groups). The dentin slabs were etched by phosphoric acid and treated with either DMA or distilled water before bonding by using an etch-and-rinse adhesive system as standard clinical protocol (n = 20 in each group). μTBS test was performed before and after thermocycling (×2500 cycles at 5 °C and 55 °C). The morphology and quality of dentin/adhesive interfaces or the fractured interfaces were examined by scanning electron microscopy (SEM). Mean μTBS (MPa) values of the DMA group vs. the DW group were 27.10 ± 11.34 vs. 21.30 ± 6.06 (p < 0.05) before thermocycling and 25.75 ± 8.74 vs. 19.87 ± 6.59 (p < 0.05) after thermocycling. SEM observation of dentin–resin binding interface showed that the DMA group had lesser defects than the DW group. Our study revealed that mussel wet adhesion inspired catechol-functionalized DMA may increase the bonding strength and improve the integrity of the interface of dentin adhesive when used as a dental primer.

Effect of Non-Thermal Atmospheric Plasma on Micro-Tensile Bond Strength at Adhesive/Dentin Interface: A Systematic Review.

Objective: The objective of this review was to evaluate the effect of non-thermal atmospheric plasma (NTAP) on adhesives resin–dentin micro-tensile bond strength (μTBS) in previously published studies. Methods: Electronic search was conducted using the Medline, Cochrane library, and Scopus databases. The included studies were laboratory studies that investigated the effect of NTAP on adhesives μTBS to coronal dentin. Studies that evaluated the effect of NTAP on bond strength to indirect substrates, enamel or root dentin, were excluded. The methodological quality of included studies was assessed. Results: Thirteen studies were included in this systematic review. All the included studies were considered to have a medium risk of bias. NTAP significantly improved μTBS at 24 h or after short-term aging in five studies (38.5%) and both immediate and after long-term aging in 5 studies (38.5%). In two studies (15.4%), NTAP resulted in a short-term material-dependent effect that was not stable after long-term aging. Interestingly, in one study (7.7%), NTAP had a positive effect only in the etch-and-rinse (ER) mode after long-term aging. Conclusion: Within the limitations of this systematic review, NTAP application could enhance resin–dentin μTBS of ER adhesives or universal adhesives (UAs) applied in the ER mode. In the ER mode, the rewetting step after NTAP seems to be unnecessary. Because of the limited information currently available in the literature, further studies are required to evaluate the effect of the NTAP application on self-etch (SE) adhesives or UAs applied in the SE mode.

Hydroxy acids for adhesion to enamel and dentin: Long-term bonding performance and effect on dentin biostability

ObjectivesTo test the demineralization potential, bonding performance, and dentin biostability when using hydroxy acids for etching enamel and dentin. MethodsSurface microhardness, roughness and depth of demineralization were investigated after etching enamel and dentin with 35 % glycolic acid (Gly), tartaric acid (Ta), gluconic acid (Glu), gluconolactone (Gln), or phosphoric acid (Pa) (n = 5/group). Dentin microtensile bond strength (μTBS) after 24 h or 1 year of bonding (n = 8 teeth/group) and enamel shear bond strength (SBS) after 24 h (n = 10 teeth/group) were obtained. In dentin, failure mode was classified as adhesive, cohesive in dentin/resin, or mixed. Dentin biostability was assessed by loss of dry weight and collagen degradation after 30-day incubation (n = 10 beams/group). Statistical analysis consisted of ANOVA with post-hoc Tukey’s HSD, Tukey-Kramer test, Bonferroni correction, and Fisher’s exact tests (α = 0.05). ResultsGly showed better or similar results than Pa for enamel microhardness and dentin roughness, while no significant differences were observed among Ta, Glu, and Gln (p > .05). Hydroxy acids produced significantly shallower demineralization than Pa (p < .05). Gln resulted in the lowest SBS and μTBS, while Gly, Glu, Ta, and Pa showed no significant difference. There was no significant difference in μTBS between 24 h and 1 year of storage. The association between failure mode and etchant was statistically significant after 24 h only (p < .001). Hydroxy acids resulted in higher dentin biostability than Pa (p < .05). ConclusionsGly, Glu and Ta resulted in adequate bonding performance and reduced dentin degradation and are potential alternative etchants to improve long-term stability of adhesive restorations. Clinical significanceThis study supports the potential use of hydroxy acids as alternative etchants when bonding to enamel and dentin and demonstrates that specific acids are more suitable to be used in adhesion since they result in appropriate bond strength and less dentin degradation.

Effect of chemical cross-linkers on surface topography and microtensile bond strength of sound dentin: An in vitro study.

Aim and Objectives:The aim of the study was to investigate the effect of two different collagen cross-linking agents proanthocyanidin (Grape seed extract [GSE] and 1-Ethyl-3-(3-dimethylaminopropyl) carbodiimide) on the surface topography of etched dentin and microtensile bond strength (μTBS) of resin dentin bond.Materials and Methods:Fifty-two sound human 3rd molars were collected, and their occlusal surfaces were ground flat to expose dentin. Dentin surfaces were etched using phosphoric acid and then teeth were randomly divided into four groups, according to the dentin treatment: Group 1: wet bonding technique, Group 2: dry bonding technique, Group 3: 6.5% proanthocyanidin, and Group 4: 0.1M carbodiimide. Scanning electron microscope analysis was done for twenty specimens (n = 5 per group) at ×10,000 and ×30,000 magnification. Remaining 32 specimens were restored with TETRIC N-Bond adhesive systems and resin composite. After 24 h, teeth were sectioned to produce a cross-sectional surface area of 1.0 mm2 and tested for μTBS.Statistical Analysis:Data were statistically analyzed using ANOVA and post hoc least significant difference test (P < 0.05).Conclusion:When acid-etched dentin is treated by 6.5% proanthocyanidin (GSE) and 0.1M carbodiimide, followed by application of adhesives, it results in increased μTBS due to cross-linking of collagen fibrils.

Comparative Evaluation of Different Antioxidants on Reversal of Microtensile Bond Strength of Composite Resin in Endodontically Treated Tooth Surface

Introduction: The use of Sodium Hypochlorite (NaOCl) as an endodontic irrigant changes the properties of dentine and lowers the bond strength of resin cements to dentine. But it can be reversed by the use of antioxidants. Aim: To evaluate the effect of different antioxidants for restoring adhesion potential/reversal of microtensile bond strength of dentin of the pulp chamber treated with NaOCl and Ethylenediaminetetracetic Acid (EDTA). Materials and Methods: It was a laboratory based experimentalin-vitro study in which 40 freshly extracted human incisors were selected and cut to expose the pulp chamber dentin. The specimens were distributed into five groups: Group I samples were irrigated with 5.25% NaOCl for 30 minutes followed by 17% EDTA for 3 minutes and final rinse was done with 5.25% NaOCl (Positive control). Group II samples were treated with distilled water only (Negative control). In Group III, samples were treated same as in group I followed by 10% Sodium Ascorbate (SA) for 10 minute. Samples of group IV samples were also treated as in group I followed by application of 5% solution of Alpha tocopherol with for 10 minutes. Group V samples were treated same as in group I followed by rinse with 5% solution of Sodium Thiosulphate (Na2S2O3) for 10 minutes. Composite resin build up was performed and interface was tested by using Universal testing machine for Microtensile bond strength. The resulting data was analysed by one-way Analysis of Variance (ANOVA) and Mann-Whitney U test (p&lt;0.05). Results: The results demonstrated that irrigation with 5.25% NaOCl and 17% EDTA produce significant (p&lt;0.05) reduction in resin dentin bond strength but this can be reversed by application of 5% Na2S2O3. Highest bond strength was observed in group V (22.38±0.84) and lowest for group I (15.38±1.22). Conclusion: Dentin bond strength was significantly reduced when bonding was performed immediately after use of NaOCl. Use of antioxidants after final irrigation with NaOCl can be recommended for better bonding of composite resin.

Morphological surface analysis and tensile bond strength of the immediate dentin sealing submitted to different temporary cement removal treatments

The aim of this study was to evaluate the morphological surface and the microtensile bond strength (μTBS) of the immediate dentin sealing (IDS) submitted to four different methods for removing temporary cement. Molar teeth received IDS with adhesive system (Adper Scotchbond Multipurpose, 3 M ESPE). Temporary restorations were made with eugenol-free temporary cement (RelyX Temp NE, 3 M ESPE). After the storage (7 days; 37 °C), the samples were submitted to four methods for removing temporary cement: periodontal curette (PC); sodium bicarbonate sandblasting (SB); aluminum oxide sandblasting (AO); and abrasion with diamond bur (DB). The control group (C) received no treatment. The morphological surface analysis (n = 2) and IDS thickness (n = 3) were analyzed using scanning electron microscopy (SEM). Resin composite blocks (Filtek Z250, 3 M ESPE) were produced and cut into sticks (~1 mm2) for μTBS (n = 9). Fracture patterns were analyzed on stereomicroscope and classified as adhesive, mixed, cohesive-dentin or cohesive-resin. Data were submitted to Shapiro-Wilk test and one-way ANOVA followed by Tukey's post hoc test (α = 0.05). PC and SB groups showed the lowest and the highest μTBS values, respectively (ρ < 0.05). The adhesive failure pattern was more frequently observed in all groups. All methods for removing temporary cement promoted morphological surface changes. SB had the best surface morphology and temporary cement removal. IDS thickness showed no significant difference for all groups. The SB method promoted the highest μTBS, removing the temporary cement without jeopardizing the IDS thickness.

Microtensile dentin bond strength and interface morphology of different self-etching adhesives and universal adhesives applied in self-etching mode

To evaluate the microtensile dentin bond strength (BS) and dentin-adhesive morphology of three self-etching bonding systems and three universal adhesives applied in self-etching mode. Four single-step adhesives: G-Premio BOND (GPB), Bond Force II (BOF), Prime&Bond Active (PBA), and Adhese Universal (ADU); and two two-steps adhesives: Clearfil SE Bond (CSB) and Clearfil SE Bond 2 (CS2) were tested. Dentin surfaces of extracted third molars were prepared for microtensile bond strength test using adhesives applied according to the manufacturers’ instructions and restored with resin composite. Restored teeth (n = 8) were sectioned to obtain beam samples that were tested after 24 h and 1 year of water storage. Data were analyzed by two-way ANOVA repeated measures and Tukey's test (α = 0.05). The micromorphology of dentin-adhesive interfaces (n = 3) was analyzed by scanning electron microscopy (SEM) at 2.000× magnification. Self-etching adhesives exhibited different bond strength values at 24 h evaluation, which ranged from 20.7 to 77.9 MPa. PBA, ADU, CSB, and CS2 showed significantly higher dentin bond strength than GPB and BOF. These two single-step adhesives presented the lowest dentin bond strengths for both storage times, and interfacial study by SEM analysis revealed short and few resin tags formations. Water-storage for 1 year did not reduce the dentin bond strength of all adhesives tested. All self-etching and universal adhesives tested presented stable bond strength over one year of water storage. Both two-step self-etching adhesives yielded immediate and long-term higher dentin bond strength than most single-step adhesives tested.

Influence of flavonoids on long-term bonding stability on caries-affected dentin

To evaluate the effect of experimental dentin pre-treatment solutions formulated with different flavonoids on microtensile bond strength (μTBS), nanohardness (NH) and ultra-morphological characteristics of artificial caries-affected dentin (CAD) bonded using a universal bonding system. A microbiological method was used to create an artificial CAD in 91 human molars. Five experimental pre-treatment solutions were created using the following flavonoids: quercetin (QUE); hesperidin (HES); rutin (RUT); naringin (NAR), or proanthocyanidin (PRO). A placebo solution (PLA) with no flavonoids added was also evaluated. The flavonoids or placebo solutions were applied to the CAD prior to the application and photoactivation of a universal adhesive (Scotchbond Universal, 3M Oral Care). A control group (CON), in which only the bonding agent was applied without any flavonoid solution, was also evaluated. A 3-mm-thick block of resin composite (Opallis, FGM) was built up on the flat bonded CAD surfaces and was light-cured following the manufacturer's instructions. Specimens were sectioned to obtain resin-dentin slices and sticks (cross-sectional area of 0.8 mm2). The μTBS, NH, and confocal ultramorphology analysis of resin-dentin interface was evaluated at 24 h and after thermo-cycling aging (25,000 cycles). The results were analyzed using 2-way ANOVA followed by Bonferroni's post hoc test (pre-set α = 0.05). The specimens from groups QUE, NAR, and RUT presented greater μTBS values than those from CON group (p<0.05). Specimens from some of these experimental groups presented greater nanomechanical properties (p<0.05), and no morphological degradation at the resin-dentin interface after aging. The use of exogenous cross-linkers as dentin pre-treatment before bonding procedures may represent a suitable strategy to improve the longevity of universal adhesive systems applied to caries-affected dentin.